#include "bits/stdc++.h"
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define vi vector<int>
#define all(a) a.begin(),a.end()
typedef pair<int,int> P;
const long long mod=998244353;
const long long inf=1ll<<61;
int kj[600006],kji[600006];
int modpow(int a,int x){
  int res=1;
  while(x){
    if(x&1)res=res*a%mod;
    a=a*a%mod;
    x>>=1;
  }
  return res;
}
void setkj(){
  kj[0]=kji[0]=1;
  for(int i=1;i<=600002;i++){
    kj[i]=kj[i-1]*i%mod;
    kji[i]=modpow(kj[i],mod-2);
  }
}
int comb(int r,int c){
  if(r<c)return 0;
  return kj[r]*kji[c]%mod*kji[r-c]%mod;
}

signed main(){
  setkj();
  int n,m,a,b;cin>>n>>m>>a>>b;
  int ans=0;
  for(int i=0;i<=b;i++){
    int d=i-(n-1)*a;
    if(d<0)continue;
    ans+=comb(n-1+d-1,d)*(m-i)%mod;
    ans%=mod;
  } 
  cout<<ans*kj[n]%mod<<endl;
  assert(2<=n&&n<=100000);
  assert(2<=m&&m<=300000);
  assert(1<=a&&a<=b&&b<=m-1);
}